Floating deck for storage tank



March 26, 1968 c. CREITH 3,374,913

FLOATING DECK FOR STORAGE TANK Fi led Jan. 25, 1966 2 Sheets-Sheet 1FIG- I INVENTOR. LOU 6. CR1. T H

[16-2 Bl/wgmw ATTOPNFV March 26, 1968 L. c. CREITH 3,374,918

FLOATING DECK FOR STORAGE TANK Filed Jan. 25, 1966 2 Sheets-Sheet 5/ Z0A; A, 117;; '1 f "WWW -3Z INVENTOR. LOU C CHE/TH dm u A T TORNE Y UnitedStates Patent 3,374,918 FLOATING DECK FOR STORAGE TANK Lou C. Creith,Allentown, Pa., assignor to Olin Mathieson Chemical Corporation, acorporation of Viriginia Filed Jan. 25, 1966, Ser. No. 522,900 4 Claims.(Cl. 22026) ABSTRACT OF THE DISCLOSURE A floating deck for use in liquidstorage tanks is provided in which a plurality of individually buoyantpans to keep the deck afloat. In areas of the deck not occupied by saidpans, sheets of metal are provided to avoid vaporization.

This invention relates in general to an improvement in floating decksfor use within a liquid storage tank, and more particularly to such adeck having improved flotability apparatus.

Floating decks of many types and forms have been proposed and used intanks designed for the storage of various liquids. Such a deck may formthe roof of the particular storage tank, or may be a separate memberwithin a tank having a fixed roof. In either case, the deck floatssubstantially horizontally on or slightly above the surface of theliquid stored and moves upwardly and downwardly with the surface as thevolume of the liquid stored varies. Thus, protection is afforded to theliquid stored from the environment above the deck; additionally,evaporation from the area below the deck is retarded.

One form of such a deck which has been proposed comprises a frameworkcovered by a generally flat material, the framework and covering beingsupported by floats attached to, and spaced below, the framework. Whilesuch a deck achieves many of the advantages of a floating deck, it isrelatively expensive to fabricate and to erect within the storage tankto be protected.

According to the instant invention, it has been found that all of thedesired advantages of a floating deck may be achieved in a relativelyinexpensive manner by incorporating into the flat covering itself themembers yielding the flotation features. This may be accomplished ingeneral by providing as a portion of the covering of the framework aplurality of individually buoyant pans designed in shape and number soas to yield the required flotation.

A further feature of the instant invention involves the design of themembers forming the framework so as to provide below the deck aplurality of pockets formed' between the surface of the liquid storedand the covering of the deck, which pockets serve to trap any vaporsformed above the surface of the liquid stored. In this way, any leakwhich may exist in a given area of the deck is isolated from theremaining portions of the deck.

It is accordingly a principal object of the instant invention to providea new and improved floating deck for use in a storage tank containing aliquid.

A further object of this invention is to provide such a deck which isrelatively inexpensive in construction and easy to install.

It is a still further object of this invention to provide such afloating deck comprising a substantially horizontal framework, at leastone individually buoyant pan supported by said framework, the remainderof the framework being covered by a material impervious and impermeableto the liquid stored, the pan being effective to cause the framework,when in use, to float with the covering material above the level of theliquid stored.

Other objects and advantages will become apparent to those skilled inthe art as a detailed description of an 3,374,918 Patented Mar. 26, 1968exemplary embodiment proceeds with reference to the drawings which forma part hereof and in which:

FIGURE 1 is a perspective view of one form of tank in which a deckaccording to the instant invention may be employed, with a portion ofthe tank Wall shown broken away to expose the deck in the interiorthereof;

FIGURE 2 is a plan view of a portion of the framework of the instantfloating deck;

FIGURE 3 is a perspective view of a pan which may be employed with theinstant deck;

FIGURE 4 is a cross-sectional view through a portion of the instantdeck, showing in particular the connection to the framework of a pan andthe covering material; and

FIGURE 5 is a cross-sectional view similar to FIG- URE 4, illustrating amodification of the instant invention.

While it is to be understood that the instant floating deck may beemployed in any type or shape of vertical walled storage tank, FIGURE 1illustrates by way of example a floating deck 10 in use in a cylindricalstorage tank 11 having a fixed roof 12 and a center pole 13, the tank 11containing a liquid 14. The floating deck 10 effectively covers thesurface of the liquid 14 by a framework supporting a number of buoyantpans 20 and substantially flat sheets 21. The specific construction ofthe deck will be detailed below, it being understood that all componentsof the deck disclosed are of a material impervious and impermeable tothe particular liquid stored. Certain materials may, for example, be alight metal, plastic material, or fabric coated with a suitable materialsuch as a plastic material.

Considering first the construction of the framework which supports allother components, reference is had to FIGURE 2. The framework,designated generally by 15, consists of a peripheral ring 22 and a gridof beams 23 and girders 24. The peripheral ring 22 conforms inconfiguration to the perimeter of the tank 11, but is spaced laterallyinwardly from the tank walls. Within ring 22 are a plurality of spacedparallel coplanar beams 23 and a plurality of spaced parallel coplanargirders 24, shown perpendicular to beams 23. For reasons to becomeevident, the ring 22, beams 23, and girders 24 are all preferably of anL-shaped or T-shaped cross-section, notched as necessary at theirintersections.

The beams 23 and girders 24 traverse the entire area enclosed by ring 22and are interconnected in any suitable manner at intersecting points 25,as by bolts or rivets. Similarly, the beams 23 are suitably attached tothe ring 22 at points of intersection 26. To form a seal between thering 22 and the interior Walls of the tank 11, while allowing forirregularities in the tank walls as the deck moves upwardly ordownwardly, a suitable flexible but resilient sealing means 27 isattached about the periphery of ring 22.

Into certain of the rectangles formed by beams 23 and girders 24 areinserted a plurality of the pans 20, one of which is illustrated indetail in FIGURE 3. The pan 20 is designed to be individually buoyant,and comprises. a curved bottom portion 30 with integral upwardly slopingside walls 31 and integral flanges 32 extending laterally from the upperedges of the sides 31. With a given size of deck 10, the required numberof pans 20 may be readily calculated so as to insure the flotability ofthe deck 10. For example, for a deck 60 feet in diameter, it has beenfound that 50 pans 4" deep, 96" long by 17" wide and approximately .040"thick aluminum yields the required flotability when employing analuminum framework and covering of suitable dimensions.

In use, the bottom 30 of pan 20 extends downwardly into the liquidstored, with the flanges 32 being attached to the framework. To coverthe portion of the framework in the areas thereof not supporting thepans, suitably shaped sheets 21 are employed. As illustrated in FIGURE1, these sheets 21, along with the pans 20, effectively cover the entirearea of the deck 10.

Referring now to FIGURE 4, the attachment of pans 20 and sheets 21 toframework may be observed. While FIGURE 4 represents a cross-sectionthrough the deck taken parallel to a beam 23, it will be appreciatedthat the construction is such that a cross-section taken parallel to agirder 24 would be analogous. Supported on the intersection of two beams23 and two girders 24 is a pan 20, with its flanges 32 being supportedabove the upper portion of girder 24 or beam 23. Adjacent portions offramework 15 are in turn covered by sheets 21, portions thereofoverlying the flanges 32 of pan 20, The overlying portions of beams 23,girders 24, flanges 32, and sheets 21 may then all be secured togetherin any suitable manner, as by a bolt or rivet at 25. To insure aseal-tight relationship at such connections, an additional strip 40 maybe employed atop the sheets 21, the strip 40 being shown as of achanneLshaped section. Additionally, a suitable glue or adhesive may beused between the opposing portions of overlying elements to assure aseal-tight relationship.

Employing the same type of attachment indicated above, the open, upperend of the pans may, if so desired, be covered by sheets similar tosheets 21 to prevent any condensation or foreign materials from settlingin pans 20. This relationship is illustrated in the simpli fied view ofFIGURE 5, wherein a pan 20', sheets 21', and strips 40 corresponding tothe analogous elements 20, 21, and 40, respectively, are shown. Arectangular covering sheet 50 may be employed to close off the upper endof pan 20', the sheets 21 and channels 40' being oriented atop the endsof sheet 50. The remainder of the attachment would, of course, beidentical to that disclosed with respect to FIGURE 4.

Referring again to FIGURE 4, an additional feature of the instantinvention may be seen. As indicated hereinbefore, the ring 22, beams 23,and girders 24 are preferably of an L-shaped or T-shaped cross-section,Thus, the downwardly projecting portions of these members, such as 41and 42 illustrated in FIGURE 4, define vertical webs extendingdownwardly into the liquid stored. As these webs form a gridcorresponding to the grid of the framework, the webs form a plurality ofpockets above the surface 43 of the liquid 14, below the underside ofthe deck 10. Such a formation of a plurality of pockets assures that agreat portion of the vapor above the surface 43 of liquid 14 will betrapped below the deck 10 even in the event of a leak at a particulararea of the deck.

-While not shown, it will be clear to those skilled in the art thatancillary equipment normally employed with floating decks may beincorporated in the design here disclosed. For example, a plurality ofdownwardly extending feet may be attached to the framework to space thedeck 10 above the bottom of the storage tank 11 when empty, tofacilitate cleaning and maintenance. Addition: ally devices for drainingaway liquids condensed on the upper surface of the deck, gauging andsampling openings, manhole passages, and vertical cables to preventrotation of the deck may be incorporated as desired.

It is to be understood that the invention is not limited to theillustrations described and shown herein which are deemed to be merelyillustrative of the best modes of 4' carrying out the invention, andwhich are susceptible of modifications of form, size, arrangement ofparts and detail of operation, but rather is intended to encompass allsuch modifications which are within the spirit and scope of theinvention as set forth in the appended claims.

What is claimed is:

1. A floating deck for use in a storage tank containing a liquid,comprising (A) a substantially horizontal framework,

(B) a plurality of individual open top buoyant pans supported by saidframework and mounted to extend downwardly into the liquid stored, saidpans consisting of:

(1) a curved bottom portion adapted to extend downwardly into theliquid,

(2) integral sides sloping upwardly from said bottom, and

(3) integral flanges extending laterally from the upper ends of saidsides,

(C) said framework in the areas thereof not supporting said pans onlybeing covered by a substantially flat material impervious to the liquidstored,

(D) said pans being of suflicient rigidity and shape retentivity tocause said framework in use to float with said material above the levelof the liquid stored.

2. A floating deck according to claim 1 wherein said framework includesvertical web portions extending downwardly into the liquid storeddefining a plurality of pockets below said framework in which vaporabove the liquid is trapped.

3. A floating deck according to claim 1 wherein said framework comprises(A) a peripheral frame,

(B) a plurality of spaced parallel coplanar beams attached to saidperipheral frame,

(C) said frame and each of said beams including a vertical web adaptedto extend downwardly into the liquid stored,

whereby the surface of the liquid is completely covered and vapor abovethe liquid is trapped below said framework in pockets formed betweensaid frame and said beams.

4. A floating deck according to claim 3 further including a plurality ofcross-brace girders attached to said peripheral frame and each includinga vertical web adapted to extend downwardly into the liquid stored,whereby, when in use, vapor above the liquid stored is trapped inpockets delimited in part by said vertical webs of said girders.

References Cited UNITED STATES PATENTS 1,674,039 6/1928 Glass 220262,036,372 4/ 1936 Sto-ugh 22026 3,029,971 4/1962 Reynolds 220263,104,775 9/ 1963 Champagnat 22026 FOREIGN PATENTS 1,241,869 8/ 1960France. 1,247,440 10/ 1960 France.

THERON E. CONDON, Primary Examiner.

I. R. GARRETT, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,374,918 March 26, 1968 Lou C. Creith It is certified that errorappears in the above identified patent and that said Letters Patent arehereby corrected as shown below:

lines 20 and 21, and column 2, lines 63 and 67,

"flotability", each occurrence, should read floatability Column 1, lines44 and 48, "flotation", each occurrence, should read floatation Column3, lines 56 and 57, after "Additionally" insert a comma.

Column 1,

Signed and sealed this 29th day of July 1969.

(SEAL) Attest:

Edward M. Fletcher, Ir.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR.

